AC leak question

ratdude747 · Aug 18, 2017

Question:

My 1995 has a major AC leak, and I haven't had time to find the leak.

I smelled refrigerant in the vents after recharging it last... would that point to a bad evaporator? (If so, I have a very new one in a parts truck, lucky me). Just asking before I go to the trouble of pulling it from said parts truck (front right side smashed, might be "fun" to access).

adsm08 · Aug 18, 2017

Yes. Probably the evap.

ratdude747 · Aug 20, 2017

Made the swap today... Since the wrecked truck saw a lot of HVAC repairs in the last year and a half, I swapped a lot:

Evaporator
High pressure line (condesor to evaporator)
Variable orifice tube
Blower motor resistor (was replaced a month before the wreck, and the one that came out wasn't looking too good)
O-rings at all connections opened (after a cleaning in alcohol and soaking in PAG oil, good as new compared to the 23 year old ones that came out)

I did not swap the accumulator, as the old one was actually rust free (on the sheet metal parts that matter) and unlike the wrecked truck (which had a bad compressor shaft and torn shaft seal), still had a little bit refrigerant pressure (and thus, shouldn't be saturated).

Basically, I replaced everything that was recently replaced and was compatible between the wrecked 3.0 and the running 4.0. Good thing I swapped high pressure lines, as the old one had 3 cracks in it.

Vacuumed it to 30 inHg for half an hour, let it sit for 30 mins (no movement of needles), then recharged it. Before final assembly, I added a few ounces of PAG oil to the accumulator, as a disproportionate amount of oil was lost in the high pressure line (which was dyed orange, not the usual yellow-green???).

The good news is she's running cold at idle and when running... at idle with the fan to low, the accumulator was frosted up. The bad news is on the way home from my parents' house (where my dead ranger lives), I got a lot of howing/fart can noise from the variable orifice tube (intermittent, possibly linked to compressor cycling?). No refrigerant smell in the truck either... and that's with all my AC serving gear/supplies sitting in the passenger seat.

Is such noise normal with a variable orifice tube? Or did I not charge it enough? Too much charge? I winged it a bit as I started with a partial can... Whoops?

55trucker · Aug 21, 2017

The entire system only needs approx 9 oz of oil, did you check the volume in the compressor before you took everything else apart & started adding?

rule of thumb for components is what you drain out is what you replace with....

the compressor.....open it up & drain it....

2 oz for a *new* accumulator, & 1 oz for a *new* condenser, 3 oz for a *new* evaporator core as they would be shipped dry.

The alloy lines don't necessarily count where volume is concerned seeing as the gas & oil are moving & don't have a reservoir situation where fluid can accumulate at the bottom, but if there was a major catastrophic loss then 2 oz would be considered needed.

I'm curious as to which tube you used........the red or the black?

red is above 105F
black is below 105F

regular would be the blue

I take it that you did not have a set of gauges with you to monitor the suction & the discharge side as you were charging. The system should hold 30 oz, how much did you put in?

ratdude747 · Aug 23, 2017

I did in fact use a proper set of Gauges:

https://www.harborfreight.com/ac-r134a-manifold-gauge-set-60806.html

And pump:

https://www.harborfreight.com/automotive-motorcycle/refrigeration/3-cfm-two-stage-vacuum-pump-60805.html

I guesstimated the oil based on how much came out... I didn't add a huge amount. I figured most was either in the compressor or in the accumulator, both of which were reused. All I know is a bunch came out of the high pressure line I swapped while not as much came out of the one I put in.

As for charging, IIRC it's actually 23 oz. for the 1995-1997 application. That's what every source I've seen has said. I usually do 2 12oz cans figuring one oz won't hurt and that amount is probably lost in the process anyway. I tried to get the 2nd full can to as empty as the partial I started with (didn't have a scale to weigh it

)

----

I might still have a leak... seems to be acting like it's low again. I'll give it a few more days to confirm it.

I do have a sniffer but it doesn't work the best. It's one of these:

http://products.inficon.com/en-us/product/detail/tek-mate-refrigerant-leak-detector?path=products/pg-servicetoolsforhvac-r

Probably needs a new sensor and filter as it was a $50 ebay find. Or not. I'll have to see.

The smell did come back (less strong), which makes me think it's a red herring and something else is shot... knowing my luck another worn compressor shaft (a new compressor isn't in the cards).

55trucker · Aug 23, 2017

I do now see the same info you quoted,

my 98 system holds 30 oz, seems the 95-97 condenser & accumulator are slightly smaller,

try giving the engine bay a complete bath to wash out any residual odours,

put the gauges back on & note the static pressure of the system when not in use

AC leak question

ratdude747

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